Asymetry dependence of proton optical potential

In the optical model studies, the half-value radius of nuclear potential is adopted to vary as Asup(1/3). However, it is known from various studies that at least in isotopic sequences, the half-value radius increases less rapidly than Asup(1/3). This is easily resolved by considering the concept of equivalent sharp radius. The proton elastic scattering data for sup(64,66,68)Zn at 30 Mev, for sup(64,66,68,70)Zn at 50 Mev, for sup(112,114,116,118,120,122,124)Sn at 30 Mev and sup(144,148,150,152,154)Sn at 50 Mev have been analysed using simple optical model, with above mentioned modification, with a view to know the isospin dependence of optical potential parameters. In addition to finding isospin dependence of parameters, the volume integral of imaginary potential per nucleon is found to vary linearly with the asymmetry parameter (N-Z)/A. This taken along with similar variation for Q value for (p,n) reactions may lead to better understanding of the imaginary potential. (author)